Hydrogen generator

ABSTRACT

A hydrogen generator constituted by a voltaic cell having a reactive magnesium electrode and a non-reactive electrode immersed in a salt-water electrolytic bath, a load being connected between the electrodes to cause a current flow in the cell resulting in an electrochemical reaction in which the magnesium is decomposed to produce hydrogen and in electrolysis in which the water is decomposed to produce hydrogen. In order to minimize polarization and other factors which diminish the production of hydrogen, the solution is circulated through an external flow loop having a pump interposed therein to draw the electrolyte from the bottom of the bath and to return it to the top thereof, the pump being powered by voltage derived from the cell.

United States Patent [1 1 Pacheco 14 1 July 1,1975

[ HYDROGEN GENERATOR [75] Inventor: Francisco Pacheco, Hewitt, N1].

[22] Filed: Nov. 14, 1973 [21] Appl. No.: 415,638

3,238,070 3/1966 Porter 136/160 3,256,504 6/1966 Fidelman 204/2483,305,404 2/1967 Sundberg 136/160 3,542,598 11/1970 White et a1. 136/100R Primary Examiner-John H. Mack Assistant ExaminerD. R, Valentine [57]ABSTRACT A hydrogen generator constituted by a voltaic cell having areactive magnesium electrode and a nonreactive electrode immersed in asalt-water electrolytic bath, a load being connected between theelectrodes to cause a current flow in the cell resulting in anelectrochemical reaction in which the magnesium is decomposed to producehydrogen and in electrolysis in which the water is decomposed to producehydrogen. In order to minimize polarization and other factors whichdiminish the production of hydrogen, the solution is circulated throughan external flow loop having a pump interposed therein to draw theelectrolyte from the bottom of the bath and to return it to the topthereof, the pump being powered by voltage derived from the cell.

10 Claims, 2 Drawing Figures 1 HYDROGEN GENERATOR BACKGROUND OF THEINVENTION This invention relates generally to the production ofhydrogen, and more particularly to a hybrid technique for this purposeinvolving both an electrochemical action and electrolysis.

Substantial amounts of hydrogen are used industrially in oxy-hydrogenand atomic hydrogen flames for high-temperature welding, in the fixationof nitrogen as ammonia, in the hydrogenation of fatty oils andunsaturated hydrocarbons, and in the formation of methyl alcohol. Inrecent years it has been recognized that hydrogen may well be the idealfuel for internal combustion and other engines, rather than gasoline orother hydrocarbons, for when a mixture of hydrogen and air is ignited ina combustion chamber to produce motive power, the combustion product ispure steam, rather than noxious pollutants such as carbon monoxide andunburned hydrocarbons. Moreover, with hydrogen as the fuel, it becomespossible to operate the engine at lower temperatures and thereby tominimize the emission of oxides of nitrogen.

A number of experimental vehicles using hydrogen as a fuel have beendemonstrated and widely publicized. Thus in the Sept. 17, 1973 issue ofthe New York Times is an article entitled NASA Testing Hydrogen inGasoline to Cut Fumes", it is noted that Over the years, there has beenmuch speculation and some work on the idea of using hydrogen, with itsenormous power and ready availability, to power autos. In fact, hydrogenhas been increasingly looked upon as the most promising long-term answerto the worlds power needs as fossil fuels become exhausted. But whilethe use of hydrogen for this purpose has been the subject of manytechnical papers, there has been no significant commercilization of thisconcept.

A major factor which has heretofore precluded a commercially-feasiblehydrogen-fueled automobile or other engine is the cost of producinghydrogen, for with known techniques the cost of hydrogen in an amountwhose energy content in terms of BTUs is equivalent to the amount ofgasoline required to fuel a car for a given number of miles. greatlyexceeds the gasoline cost.

Hydrogen is prepared commercially by the electrolysis of aqueous saltsolutions, by the reaction of dilute sulfuric acid and a metal such aszinc, by the reaction of iron with steam and by various othertechniques, all of which are relatively expensive.

In order to reduce the cost of manufacturing hydrogen, particularly foruse in operating automotive engines, there is disclosed in my prior US.Pat. No. 3,648,668, a hydrogen gas generator including a magnesiumelectrode and a carbon electrode immersed in a salt-water electrolyte, avariable load resistance being connected between the electrodes tocontrol the rate at which hydrogen is generated. The entire disclosurein US. Pat. No. 3,648,668 is hereby incorporated by referencev With theelectrodes open-circuited, there is a chemical reaction between themagnesium electrode and the salt-water electrolyte which acts slowly toevolve hy drogen gas. When the circuit between the electrodes is closedby the variable load resistance, an electric current is caused to flowto a degree depending on the resistance of the load. The rate ofhydrogen production varies in proportion to the current flow which isinversely related to the value of load resistance.

The combination of a magnesium and carbon or steel electrode in asalt-water electrolyte acts as a voltaic cell and when current flowstherein, the reaction in such that the magnesium electrode is decomposedto form magnesium hydroxide, this reaction continuing until themagnesium electrode is entirely decomposed. And because theelectrochemical reaction gives rise to a galvanic voltage between theelectrodes, this results in electrolysis of the water whereby hydrogenis liberated at the cathodic electrode (magnesium) and oxygen at theanode electrode (carbon or steel). Thus two molecules of hydrogen areformed for each molecule of oxygen.

lnasmuch as hydrogen is yielded by the cell both as a consequence of thedecomposition of magnesium and because of electrolysis in which thedecomposing magnesium serves concurrently as a cathode electrode, theoverall amount of hydrogen produced by this hybrid system is far greaterthan that produced by the known reactions of magnesium in a saltsolution.

It has been found, however, that with a hydrogen generator of the typedisclosed in my prior patent, the volume of hydrogen generated at theoutset of operation is large, but with continued operation this volumetends to diminish because of polarization and other factors, therebymaking the generator less efficient. It has been found, for example,that the salt water solution which is initially neutral becomesincreasingly base and that when this happens, the production of hydrogenis reduced. Also, with continued operation, the solution becomes heated,and while this is beneficial up to about to F, at higher temperatures itgives rise to a reduction in hydrogen output.

SUMMARY OF THE INVENTION In view of the foregoing it is the main objectof this invention to provide a galvanic hydrogen generator making use ofa magnesium electrode in a salt-water solution to produce hydrogen bothby electrochemical reaction and by electrolysis, the hydrogen output ofthe generator being undiminished throughout its useful life.

More particularly it is an object of this invention to provide ahydrogen cell of the above-identified type capable of producing hydrogenin large quantities and at relatively low cost, the salt-waterelectrolyte being circulated continuously to minimize polarization andother factors tending to diminish the output.

Also an object of the invention is to provide a hydrogen generator forthe above-identified type wherein the voltage generated by the cell isexploited to operate a pump for circulating the electrolyte.

Still another object of the invention is to provide a hydrogengenerating system in which the voltage generated in one or moremagnesium cells wherein hydrogen is produced electrochemically alsoserves to effect electrolysis in these cells and in an externalelectrolysis cell.

Briefly stated, these objects are attained in one preferred embodimentof the invention wherein a voltaic cell constituted by a magnesiumelectrode and a carbon or steel electrode immersed in a salt-water bathsuch as sea water, is provided with an external flow loop having a pumpinterposed therein, preferably powered by the cell voltage, the loopdrawing electrolyte from the bottom of the bath and returning it to thetop of the bath whereby the electrolyte is continuously circulated. Theloop may include a heat exchange coil to reduce the temperature of theelectrolyte.

In another embodiment of the invention, the loop includes anelectrolysis cell having a pair of like electrodes the rein to which avoltage derived from the magnesium cell is applied, whereby the hydrogenliberated in the electrolysis cell is added to the hydrogen generated inthe voltaic cell and the liberated oxygen is fed to a separate output.

OUTLINE OF THE DRAWING For a better understanding of the invention aswell as other objects and further features thereof, reference is made tothe following detailed description to be read in conjunction with theaccompanying drawing, wherein:

FIG. I is a schematic diagram of one preferred embodiment of theinvention, and

FIG. 2 is a schematic diagram of another preferred embodiment of theinvention.

DESCRIPTION OF THE INVENTION First Embodiment Referring now to FIG. 1,there is shown a hydrogengenerating voltaic cell in accordance with theinvention in which a salt or sea water electrolyte is contained in atank 10, preferably fabricated of a non-corrosive metal provided with aninsulating liner, or of a highstrength synthetic non-reactive plasticmaterial. The cover 11 of tank includes a gas-discharge outlet 12.

Supported within tank 10 and immersed in the electrolyte is an activemagnesium electrode 13 and an inactive electrode 14, preferably composedof carbon, steel or other conductive material which is nonreactive. Thetank is hermetically sealed except for the outlet provided for theescape of hydrogen gas. Electrodes l3 and 14 are interconnected by avariable load resistor 15. This load may also include other electricaldevices such as lamps and motors.

When the electrodes are interconnected by the load resistor, a currentflows in the cell with an intensity determined by the resistance of theload the higher the resistance, the smaller the current. The rate ofhydrogen production is proportional to current flow, this rate beinggreatest where the load is effectively a short cir cuit. In practice, inorder to limit the amount of hydrogen generated to the demand therefor,a control circuit may be provided which is responsive to the level ofdemand and functions to vary the load resistor to meet but not exceedthe demand.

The electrochemical reaction which accompanies the decomposition of themagnesium electrode results in the formation of magnesium hydroxidewhich is deposited in the bottom of the tank. When the magnesiumelectrode is consumed, it must be replaced. The magnesium hydroxide maybe processed to recover its magnesium content. Concurrent with theelectrochemical activity is electrolysis which liberates hydrogen. Nosignificant amount of liberated oxygen passes out of the cell, for theoxygen becomes involved in the electrochemical reaction and also formshydrogen peroxide. Inasmuch as the cell itself generates the voltage forelectrolysis, the cell operates as an auto-electrolysis device requiringno external voltage source.

As previously noted, the electrolyte is initially neutral. However, inthe course of operation, the electrolyte becomes base in character, itstemperature rises and polarization occurs, all of which act to reducethe hydrogen output. These adverse effects are minimized by means of anexternal flow loop 16 which communicates at its input end with thebottom of the electrolyte bath in tank 10 and at its return end with thetop of the bath.

lnterposed in loop 16 is a strainer or filter 17 to collect themagnesium hydroxide sediment, a pump 18, a heat exchange coil 19 and acontrol valve 20. Pump 18 is powered by voltage derived from cell 10,and since this voltage in a single cell is less than l.5 volts, asuitable D-C voltage multiplier may, in practice, be used to step upthis voltage to a higher operating voltage, such as 24 volts.

When the pump is operative, the electrolyte is drawn from the bottom ofthe bath by the pump and carried through the filter 17 to removesediment therefrom, the electrolyte then passing through cooling coil 19before it is returned to the top of the bath. Thus the electrolyte iscontinuously circulated, in the course of which it is purified andcooled to maintain operation of the cell at optimum efficiency.

Second Embodiment In the arrangement shown in FIG. 2, a group ofidentical voltaic cells 1, 2, 3 and 4 is provided. This group is formedin a common tank 21 divided into four cells by partitions 22, 23 and 24.Each cell is equipped with a magnesium electrode Mg and a carbonelectrode C. The cells are serially connected to an adjustable loadresistor 25, so that the voltage applied to the load is 4 times thevoltage of a single cell. Obviously, in practice the arrangement may bescaled to define a greater number of voltaic cells.

The four cells formed in the tank have a common salt-water electrolyte,and in order to permit this electrolyte to circulate freely from cell tocell, each partition is provided with a lower port, such as port 22A,and an upper port 228.

Coupled to the tank 21 is an external flow loop whose lower branch 26Ahas a pump 27 interposed therein and whose upper branch 268 has a filter28a interposed therein. This loop passes through an electrolysis cell 28having a pair of spaced carbon electrodes Ce immersed therein, whichelectrodes are isolated from each other by a divider 29 serving tosegregate hydrogen gas evolved at the negatively-biased carbon electrode(cathode) and the oxygen evolved at the positivelybiased carbonelectrode (anode).

The voltage for operating the electrolysis cell is taken from acrossload resistor 25. This voltage is also used to operate pump 27. Noelectrochemical action takes place in the electrolysis cell, for in thiscell it is only water which is decomposed. Since this water is derivedfrom the volt-aic cells where hydrogen peroxide is produced, thishydrogen peroxide is subjected to electroly- SIS.

In order to accumulate hydrogen from both the voltaic cells and theelectrolysis cell, a manifold 30 is provided which is coupled to all ofthese cells. A separate outlet 31 is provided for the oxygen output.

It has been found that in the course of operation, the electrolyte involtaic cells 1, 2, 3 and 4 which is initially neutral in characterbecomes base, whereas the electrolyte in the electrolysis cell 28becomes acid. But because of the continuous circulation of theelectrolyte from the voltaic cells through the electrolysis cell andback to the voltaic cells, the intermingling of the acid electrolytewith the base electrolyte acts to maintain the electrolyte generallyneutral. thereby optimizing the hydrogen output.

While there has been shown preferred embodiments of the invention, itwill be appreciated that many changes and modifications may be madewithout, however, departing from the essential spirit of the invention.For example, while circulation of the electrolyte has been realized bymeans of an external loop incorporating a pump, one can by providing acell whose electrodes are immersed in the open sea in an arrangement inwhich the saline sea water freely circulates, obtain a similar result.

I claim:

1. A hydrogen generator comprising:

A. at least one voltaic cell having an active magnesium electrode and anon-active electrode adapted to be immersed in a salt-water electrolytecontained in a tank having a hydrogen outlet above the level of saidelectrolyte,

B. a variable load resistor external to the cell and connected acrossthe electrodes to produce a current in said cell resulting in theproportional production of hydrogen which is discharged through saidoutlet, a voltage being developed across said load resistor, and

C. an external flow loop communicating with said tank adjacent the lowerand upper ends thereof to effect continuous circulation and cooling ofsaid electrolyte to minimize polarization and other adverse effects,said loop including an electricallyoperated pump connected to said loadresistor and powered by said voltage, said pump functioning to draw theelectrolyte from the lower end of the tank and to return it to the upperend thereof.

2. A generator as set forth in claim 1, wherein said loop furtherincludes a heat-exchange coil to cool said electrolyte.

3. A generator as set forth in claim 1, wherein said loop furtherincludes a filter to remove contaminants from the electrolyte.

4. A generator as set forth in claim 1, wherein said loop furtherincludes an electrolysis cell having a pair of electrodes thereinconnected across said load resistor, the hydrogen evolved in saidelectrolysis cell being combined with that produced by said voltaiccell.

5. A generator as set forth in claim 1, wherein said non-activeelectrode is carbon.

6. A generator as set forth in claim 4, wherein said pair of electrodesare carbon electrodes.

7. A generator as set forth in claim 1, wherein said tank is dividedinto a plurality of voltaic cells by partitions having ports therein topermit the interflow of said electrolyte, said voltaic cells beingseriallyconnected to said load resistor.

8. A generator as set forth in claim 4, wherein said electrolysis cellincludes a divider between said pair of electrodes to separate evolvedoxygen from evolved hydrogen.

9. A hydrogen generator as set forth in claim 1, wherein said cellelectrodes are immersed in the open sea to provide a freely-circulatingsalt-water electro l te.

10. A hydrogen generator as set forth in claim 1, wherein said externalflow loop includes an electrolysis cell through which said electrolytecirculates whereby as the electrolyte in the voltaic cell becomeschemically base in character in the course of operation, the electrolytein the electrolysis cell becomes acid in character to an extentmaintaining the circulating electrolyte substantially neutral tooptimize the hydrogen output.

1. A HYDROGEN GENERATOR COMPRISING: A. AT LEAST ONE VOLTAIC CELL HAVINGAN ACTIVE MAGNESIUM ELECTRODE AND A NON-ACTIVE ELECTRODE ADAPTED TO BEIMMERSED IN A SALT-WATER ELECTROLYTE CONTAINED IN A TANK HAVING AHYDROGEN OUTLET ABOVE THE LEVEL OF SAID ELECTROLYTE, B. A VARIABLE LOADRESISTOR EXTERNAL TO THE CELL AND CONNECTED ACROSS THE ELECTRODES TOPRODUCE A CURRENT IN SAID CELL RESULTING IN THE PROPORTIONAL PRODUCTIONOF HYDROGEN WHICH IS DISCHARGED THROUGH SAID OUTLET, A VOLTAGE BEINGDEVELOPED ACROSS SAID LOAD RESISTOR, AND C. AN EXTERNAL FLOW LOOPCOMMUNICATING WITH SAID TANK ADJACENT THE LOWER AND UPPER ENDS THEREOFTO EFFECT CONTINUOUS CIRCULATION AND COOLING OF SAID ELECTROLYTE TOMINIMIZE POLARIZATION AND OTHER ADVERSE EFFECTS, SAID LOOP INCLUDING ANELECTRICALLY-OPERATED PUMP CONNECTED TO SAID LOAD RESISTOR AND POWDEREDBY SAID VOLTAGE, SAID PUMP FUNCTIONING TO DRAW THE ELECTROLYTE FROM THELOWER END OF THE TANK AND TO RETURN IT TO THE UPPER END THEREOF.
 2. Agenerator as set forth in claim 1, wherein said loop further includes aheat-exchange coil to cool said electrolyte.
 3. A generator as set forthin claim 1, wherein said loop further includes a filter to removecontaminants from the electrolyte.
 4. A generator as set forth in claim1, wherein said loop further includes an electrolysis cell having a pairof electrodes therein connected across said load resistor, the hydrogenevolved in said electrolysis cell being combined with that produced bysaid voltaic cell.
 5. A generator as set forth in claim 1, wherein saidnon-active electrode is carbon.
 6. A generator as set forth in claim 4,wherein said pair of electrodes are carbon electrodes.
 7. A generator asset forth in claim 1, wherein said tank is divided into a plurality ofvoltaic cells by partitions having ports therein to permit the interflowof said electrolyte, said voltaic cells being serially-connected to saidload resistor.
 8. A generator as set forth in claim 4, wherein saidelectrolysis cell includes a divider between said pair of electrodes toseparate evolved oxygen from evolved hydrogen.
 9. A hydrogen generatoras set forth in claim 1, wherein said cell electrodes are immersed inthe open sea to provide a freely-circulating salt-water electrolyte. 10.A hydrogen generator as set forth in claim 1, wherein said external flowloop includes an electrolysis cell through which said electrolytecirculates whereby as the electrolyte in the voltaic cell becomeschemically base in character in the course of operation, the electrolytein the electrolysis cell becomes acid in character to an extentmaintaining the circulating electrolyte substantially neutral tooptimize the hydrogen output.